This program represents a multidiscipline approach to the study of the reproductive endocrinology of the time period of the ovulation cycle through implantation. The hypothalamo-pituitary-ovarian axis and uterus during the ovulation cycle through implantation will be examined by a group of three Principal Investigators and three co-investigators to determine the regulation of secretion, metabolism and mechanism of action of hormones that control reproduction. This will be done by in vivo studies and in vitro incubations, using biochemical techniques for steroid and protein isolation and synthesis, subcellular fractionations, ligand-receptor interactions, radioimmunoassays, histological and ultrastructural analysis, blood flow measurements and isolated hypothalamic preparations.